The invention is an energy conservation device intended for use in providing flowing fluid through a controlled volume at an elevated temperature under conditions where conventional heating techniques are impractical or undesired and where the fluid is supplied under pressure from its source. The invention derives operating power from the mechanical energy of the pressurized fluid flow and utilizes the fluid as a working fluid in a heat engine. It operates in an open thermodynamic loop and utilizes a nozzle means for supplying high velocity flow to compress and near adiabatically condense fluids having large saturated vapor to liquid volume ratios. The device operates to accumulate thermal energy inside the controlled volume by extracting an amount of heat from fluid flowing from the controlled volume and supplying it to fluid flowing to the controlled volume sufficient to cause the fluid flowing from the controlled volume to exit at a lower temperature than that at which the fluid is supplied from its source.
An application and supporting approximations for utilizing the invention to supply heated running water in a bathroom sink are included herein but are not intended to limit the coverage of this patent. A modified version of the invention is included which shows its use to cool or deplete thermal energy from a controlled volume.